Many communication networks support some sort of connection continuity monitoring function. Operations Administration and Maintenance continuity checking (OAM CC) is an example of one such function for Asynchronous Transfer Mode (ATM) networks. According to OAM CC, cells are sent from a network element at one or both ends of a communication network connection, and a connection failure or fault, generally referred to as loss of continuity or LOC, is detected when the cells are not received when expected at the other end of the connection. Cell transmission and reception are typically accomplished by configuring an OAM CC source at a network element at one end of a connection and an OAM CC sink at a network element at the other end of the connection, as described, for example, in U.S. patent application Ser. No. 09/624,756, entitled “Network Management Support For OAM Functionality And Method Therefore”, filed Jul. 24, 2000, and incorporated in its entirety herein by reference. OAM sources inject OAM cells into a dataflow on a connection, and OAM sinks extract these cells from the dataflow for analysis. Bidirectional continuity checking is provided by configuring an OAM CC source and sink at each end of a connection.
In response to detecting LOC, a connection may be rerouted through an alternate communication path in the network. In one conventional rerouting technique, an LOC alarm is sent from a network element to a network management system, and the network management system controls rerouting of the connection. This technique, however, consumes communication network resources for transmitting alarms from network elements to the network management system and connection control signals from the network management system to network elements to reroute the connection. Network management system-based rerouting also consumes time and processing resources at the network management system.
Another connection rerouting technique provides for local connection rerouting by network elements without involvement of a network management system after a connection has been established. Where both network elements between which a connection is to be established support a local connection rerouting function, the local connection rerouting function is enabled at the network elements in response to configuration commands from the network management system when the connection is being established. The network elements then reroute the connection upon detecting LOC. In this case, an alarm may be generated at a network element, but is processed locally. Alarm transmissions to and processing by the network management system are thereby avoided. However, there are currently no mechanisms for configuring this type of reroute on LOC for a connection where a network element on either end of the connection does not detect LOC.